Field
Aspects of the present invention generally relate to an ophthalmologic apparatus that images the eye fundus of an eye to be examined.
Description of the Related Art
At present, an imaging apparatus that is capable of capturing a tomographic image of an object to be examined (an eye fundus tomographic image) with high resolution using an optical coherence tomography (OCT) which uses interference caused by low coherent light (hereinbelow, referred to as an OCT apparatus) has been put to practical use. Further, in the ophthalmologic field, a scanning laser ophthalmoscope (SLO, hereinbelow, referred to as an SLO apparatus) that captures an eye fundus surface image of an eye to be examined (a two-dimensional surface image of an object to be examined) with high resolution by laser scanning has been put to practical use. In an eye fundus examination, for the purpose of determining a region in which an eye fundus tomographic image is acquired while observing an eye fundus surface image, it is required to acquire the eye fundus surface image and the eye fundus tomographic image in a desired region on the eye fundus. Japanese Patent Application Laid-Open No. 2009-160190 discloses an ophthalmologic imaging apparatus that branches an optical path by a dichroic mirror to acquire both an eye fundus tomographic image by an OCT apparatus and a two-dimensional eye fundus surface image by an SLO apparatus.
An ophthalmologic imaging apparatus that acquires both an eye fundus tomographic image and an eye fundus surface image typically uses a refractive optical system such as a lens as an objective optical system as in Japanese Patent Application Laid-Open No. 2009-160190. A refractive optical system allows light to enter the objective optical system from the opposite side of an eye to be examined. Thus, it is relatively easy to ensure a space for synthesizing and separating an optical path without interference (contact) with the eye or the face.
In order to prevent symptoms of a small lesion from being overlooked, it is required to acquire an eye fundus tomographic image and an eye fundus surface image in a wide angle-of-view range. In this case, in a refractive optical system, in order to photograph a wide angle-of-view range without increasing the size of an apparatus, it is necessary to reduce the distance (working distance) between an eye to be examined and the optical system. When the working distance is reduced, the nose or the cheek of a subject may interfere (make contact) with the objective optical system or it may be difficult for an operator to perform a photographing support operation such as eyelid opening.
Japanese Patent Application Laid-Open No. 2014-502552 discloses an ophthalmologic imaging apparatus in which an eye to be examined and a scanning reflective mirror (a scanning unit that scans the eye fundus with light) are arranged at two focal points of an objective reflective mirror used as an objective optical system to acquire an eye fundus surface image with a compacter configuration than a refractive optical system as well as in a wide angle-of-view range.